4.2

Question 1

There are four main events in all organisms related to cell derivation. four

Question 2

9. The first main event is cell division signals. cell division signals

Question 3

10. The second main event is DNA replication. DNA replication

Question 4

11. The third main event is DNA segregation. DNA segregation

Question 5

12. The fourth main event is cytokinesis. cytokinesis

Question 6

13. Signals to divide in prokaryotes are usually external factors. external factors

Question 7

14. Nutrient concentration is an example of an external factor that signals prokaryotic cell division. Nutrient concentration

Question 8

15. Environmental conditions are an example of external factors that signal prokaryotic cell division. Environmental conditions

Question 9

16. Cell division in prokaryotes (binary fission) results in reproduction of the entire single-celled organism. binary fission

Question 10

17. Most prokaryotes have one chromosome. one

Question 11

18. A prokaryotic chromosome is often circular

Answer 11

but folded. circular

Question 12

19. The ori region on a prokaryotic chromosome is where replication starts (origin). ori

Question 13

20. The ter region on a prokaryotic chromosome is where replication ends (terminus). ter

Question 14

21. After replication in prokaryotes

Answer 14

ori regions move to opposite ends of the cell. ori regions

Question 15

22. The movement of ori regions segregates the daughter chromosomes in prokaryotes. daughter chromosomes

Question 16

23. In prokaryotic cytokinesis

Answer 16

the cell membrane pinches in. cell membrane

Question 17

24. Protein fibers form a ring during prokaryotic cytokinesis. Protein fibers

Question 18

25. New cell wall materials are synthesized during prokaryotic cytokinesis. cell wall

Question 19

26. Prokaryotic cell division results in the separation of the two cells. separation

Question 20

27. Cell division signals in eukaryotes are related to the needs of the entire organism. entire organism

Question 21

28. Eukaryotic DNA replication is more complex than in prokaryotes. complex

Question 22

29. Eukaryotes have more than one chromosome. more than one

Question 23

30. Replication in eukaryotes starts at many origins on the chromosome. many origins

Question 24

31. Replication in eukaryotes is limited to one part of the cell cycle. one part of the cell cycle

Question 25

32. Mitosis separates the newly replicated chromosomes into two new nuclei in eukaryotes. Mitosis

Question 26

33. One copy of each chromosome ends up in each daughter cell after eukaryotic DNA segregation. copy of each chromosome

Question 27

34. Eukaryotic cytokinesis proceeds differently in animal and plant cells. differently

Question 28

35. Plants have cell walls

Answer 28

which affects their cytokinesis. cell walls

Question 29

36. A mutation acquired by a bacterium will very likely be inherited by both daughter cells. both

Question 30

37. Binary fission can be best described as DNA replication

Answer 30

DNA division

Question 31

38. In a dividing bacterial cell

Answer 31

A indicates ori. ori

Question 32

39. In a dividing bacterial cell

Answer 32

the cells labeled 1 and 2 are genetically similar. genetically similar

Question 33

40. In bacterial cell division

Answer 33

the function of the ori site is that It is the origin of DNA replication. It is the origin of DNA replication

Question 34

41. DNA replication is a critical step in cell division because It ensures that each daughter cell receives an identical copy of the genome. It ensures that each daughter cell receives an identical copy of the genome

Question 35

42. If a bacterial cell is placed in an environment with limited nutrients

Answer 35

it would likely halt DNA replication until conditions improve. halt DNA replication until conditions improve

Question 36

43. If a scientist observes two distinct ori regions at opposite ends of a dividing bacterial cell

Answer 36

she can conclude that **DNA replication has completed

Question 37

44. A mutation that disrupts the function of the ori site would affect DNA replication and segregation in binary fission. DNA replication and segregation

Question 38

45. A disruption of the ori site would likely impact cytokinesis and overall cell division. cytokinesis and overall cell division

Question 39

46. Chromosomes become highly condensed before they segregate. condensed

Question 40

47. Condensation makes chromosomes easier to move into the two new nuclei. nuclei

Question 41

48. The spindle

Answer 41

a special cytoskeletal structure composed of microtubules

Question 42

49. Cytokinesis proceeds differently in plant cells (which have a cell wall) than in animal cells. cell wall

Question 43

50. The cells resulting from mitosis are identical to the parent cell in the amount and kind of DNA they contain. identical

Question 44

51. Meiosis is another mechanism for nuclear division involved in gamete formation. Meiosis

Question 45

52. Four events are required for cell division: cell division signals

Answer 45

replication of the genetic material (DNA)

Question 46

53. Prokaryotes often have just one chromosome. one

Question 47

54. Eukaryotes usually have multiple chromosomes. multiple

Question 48

55. The process of cell division is more intricate in eukaryotes. intricate

Question 49

56. Commonly

Answer 49

nutrient concentration controls whether a prokaryotic cell will begin binary fission. nutrient concentration

Question 50

57. DNA must be replicated and segregated before the cell can divide. replicated

Answer 50

segregated

Question 51

58. DNA replication and cell division are more complex in eukaryotes than in prokaryotes because eukaryotes have multiple chromosomes and more intricate regulatory mechanisms. multiple chromosomes

Question 52

59. The eukaryotic cell division cycle includes the phases through which a single cell passes to produce daughter cells. eukaryotic cell division cycle

Question 53

60. The eukaryotic cell cycle can be divided into four phases: G1

Answer 53

S

Question 54

61. The M phase includes mitosis and cytokinesis. M phase

Question 55

62. The G1

Answer 55

S

Question 56

63. DNA replication occurs during the S phase of interphase. S phase

Question 57

64. During interphase

Answer 57

the cell nucleus is visible. nucleus

Question 58

65. Typical cell functions occur during interphase. interphase

Question 59

66. The duration of the cell cycle varies considerably in different cell types. varies considerably

Question 60

67. Cells in an early embryo may have a cell cycle as short as 30 minutes. 30 minutes

Question 61

68. Rapidly dividing cells in an adult human typically complete the cell cycle in about 24 hours. 24 hours

Question 62

69. In general

Answer 62

cells spend most of their time in interphase. interphase

Question 63

70. During G1 phase

Answer 63

each chromosome is a single

Question 64

71. Variations in the duration of G1 account for most of the variability in the length of the cell cycle in different cell types. G1

Question 65

72. G1 ends at the G1-to-S transition. G1-to-S transition

Question 66

73. At the G1-to-S transition

Answer 66

the commitment is made to DNA replication and subsequent cell division. cell division

Question 67

74. During S phase

Answer 67

each chromosome is duplicated. S phase

Question 68

75. After duplication in S phase

Answer 68

each chromosome consists of two sister chromatids. sister chromatids

Question 69

76. Sister chromatids remain joined together until mitosis. mitosis

Question 70

77. During G2 phase

Answer 70

the cell makes preparations for mitosis. G2 phase

Question 71

78. Cells that do not divide usually arrest during G1 and enter G0. G0

Question 72

79. DNA is replicated during S phase. S

Question 73

80. Cell division—cytokinesis—occurs at the end of M phase. M

Question 74

81. The restriction point (R) is a checkpoint for progression through the cell cycle. restriction point (R)

Question 75

82. Specific internal signals trigger events in the cell cycle. internal signals

Question 76

83. Cell fusion experiments revealed the existence of internal signals that control the transitions between stages of the cell cycle. transitions between stages

Question 77

84. An experiment involving the fusion of HeLa cells showed that a cell in S phase produces a substance that activates DNA replication. DNA replication

Question 78

85. Nuclei of cells in G1 do not undergo DNA replication. G1

Question 79

86. Nuclei in S phase do undergo DNA replication. S phase

Question 80

87. Rao and Johnson’s hypothesis was that a cell in S phase contains an activator of DNA replication. S phase

Question 81

88. In the cell fusion experiment

Answer 81

both nuclei in the fused G1/S cell enter S phase. S phase

Question 82

89. Sendai virus was used as a tool to fuse cells experimentally. Sendai virus

Question 83

90. HeLa cells divide continuously. HeLa cells

Question 84

91. Before fusion

Answer 84

the cells in S phase were exposed to a radioactively labeled component of DNA (thymidine). radioactively labeled component of DNA (thymidine)

Question 85

92. The radioactivity labeled the nuclei of the S phase cells. nuclei

Question 86

93. Progress through the cell cycle depends on the activities of cyclin-dependent kinases

Answer 86

or CDKs. cyclin-dependent kinases

Question 87

94. A protein kinase catalyzes the transfer of a phosphate group from ATP to a target protein. phosphate group

Question 88

95. The phosphate transfer is called phosphorylation. phosphorylation

Question 89

96. A particular CDK controls the G1-to-S transition. G1-to-S transition

Question 90

97. The G1-to-S transition is a control point called the restriction point (R). restriction point (R)

Question 91

98. CDKs are not enzymatically active as protein kinases unless they are bound to another class of protein called cyclins. cyclins

Question 92

99. The binding of a cyclin activates the CDK by altering its shape and exposing its active site to substrates. shape

Question 93

100. The cyclin–CDK that controls passage from G1 to S phase is not the only such complex involved in regulating the eukaryotic cell cycle. not the only

Question 94

How many main events are there in all organisms related to cell derivation Four. What is the first main event in cell derivation Cell division signals

Question 95

What is the second main event in cell derivation? DNA replication

Question 96

What is the third main event in cell derivation? DNA segregation

Question 97

What is the fourth main event in cell derivation? Cytokinesis

Question 98

What usually signals cell division in prokaryotes? External factors

Question 99

Give an example of an external factor that signals prokaryotic cell division. Nutrient concentration

Question 100

Give another example of an external factor that signals prokaryotic cell division. Environmental conditions

Question 101

What is the name for cell division in prokaryotes? Binary fission. What does binary fission in prokaryotes result in? Reproduction of the entire single-celled organism

Question 102

How many chromosomes do most prokaryotes have? One

Question 103

Describe the typical structure of a prokaryotic chromosome. Often circular

Answer 103

but folded

Question 104

What does “ori” stand for in the context of prokaryotic chromosomes? Origin (where replication starts)

Question 105

What does “ter” stand for in the context of prokaryotic chromosomes? Terminus (where replication ends)

Question 106

What happens to the ori regions after DNA replication in prokaryotes? They move to opposite ends of the cell

Question 107

What does the movement of ori regions lead to in prokaryotes? Segregation of the daughter chromosomes

Question 108

What happens to the cell membrane during prokaryotic cytokinesis? It pinches in

Question 109

What forms a ring during prokaryotic cytokinesis? Protein fibers

Question 110

What materials are synthesized during prokaryotic cytokinesis? New cell wall materials

Question 111

What is the end result of prokaryotic cell division? Separation of the two cells

Question 112

What are eukaryotic cell division signals related to? The needs of the entire organism

Question 113

How does eukaryotic DNA replication compare to prokaryotic replication in complexity? It is more complex

Question 114

Question: How many chromosomes do eukaryotes have? More than one

Question 115

Question: Where does replication start on eukaryotic chromosomes? At many origins

Question 116

Question: When does replication occur in the eukaryotic cell cycle? Limited to one part of the cell cycle

Question 117

Question: What process separates newly replicated chromosomes into two new nuclei in eukaryotes? Answer: Mitosis

Question 118

Question: What is the outcome of eukaryotic DNA segregation in terms of chromosome copies in daughter cells? One copy of each chromosome ends up in each daughter cell

Question 119

How does eukaryotic cytokinesis differ between animal and plant cells? It proceeds differently

Question 120

What structural feature do plant cells have that affects cytokinesis? Cell walls

Question 121

Question: True or false: A mutation acquired by a bacterium will very likely be inherited by both daughter cells. True

Question 122

Question: Which of the following best describes binary fission: A. DNA replication

Answer 122

Cell division

Question 123

In a dividing bacterial cell

Answer 123

what does ‘ori’ indicate? The origin of DNA replication

Question 124

In a dividing bacterial cell

Answer 124

are the daughter cells genetically similar or different?Genetically similar

Question 125

Question: In bacterial cell division

Answer 125

what is the function of the ori site? It is the origin of DNA replication

Question 126

Question: Why is DNA replication a critical step in cell division? It ensures that each daughter cell receives an identical copy of the genome

Question 127

How might limited nutrients affect a bacterial cell’s division process? It would likely halt DNA replication until conditions improve

Question 128

Question: If a scientist observes two distinct ori regions at opposite ends of a dividing bacterial cell

Answer 128

what can she conclude? DNA replication has completed

Question 129

Question: What two processes in binary fission would be affected by a mutation disrupting the ori site? Answer: DNA replication and segregation

Question 130

What are the likely impacts of an ori site mutation on cytokinesis and overall cell division? Likely impact on cytokinesis and overall cell division (The sources don’t provide specific details on how it would impact cytokinesis without proper DNA replication and segregation

Answer 130

but it indicates there would be an impact).

Question 131

What happens to chromosomes before they segregate during cell division?Answer: They become highly condensed

Question 132

What is the cytoskeletal structure involved in moving chromosomes during segregation?The spindle

Question 133

Question: What are the cells resulting from mitosis in terms of their DNA content compared to the parent cell? Identical

Question 134

Question: What is another mechanism for nuclear division involved in gamete formation? Meiosis

Question 135

Question: How many key events are required for cell division? Answer: Four

Question 136

Question: Name the four key events required for cell division. Answer: Cell division signals

Answer 136

replication of the genetic material (DNA)

Question 137

What commonly controls whether a prokaryotic cell will begin binary fission? Nutrient concentration

Question 138

Why must DNA be replicated and segregated before the cell can divide? To ensure that each of the two new daughter cells receives a complete and identical copy of the genetic material

Question 139

Question: Why are DNA replication and cell division more complex in eukaryotes than in prokaryotes? Answer: Eukaryotes usually have multiple chromosomes

Answer 139

and the process of cell division is more intricate

Question 140

Question: What is the series of phases a eukaryotic cell passes through to produce daughter cells called? Answer: The cell cycle

Question 141

Question: Name the four phases of the eukaryotic cell cycle. G1

Answer 141

S

Question 142

Question: Which phase of the cell cycle includes mitosis and cytokinesis?M phase

Question 143

Question: What do the G1

Answer 143

S

Question 144

Question: During which phase of interphase does DNA replication occur? S phase

Question 145

Question: What is visible in the cell during interphase? The cell nucleus

Question 146

Question: Does the duration of the cell cycle vary? If so

Answer 146

among what? Yes

Question 147

Question: In general

Answer 147

do cells spend more or less time in interphase compared to M phase? More time

Question 148

What is the state of each chromosome during the G1 phase? A single

Answer 148

unreplicated DNA molecule with associated proteins

Question 149

Question: What accounts for most of the variability in the length of the cell cycle in different cell types? Variations in the duration of G1

Question 150

Question: What marks the end of the G1 phase? The G1-to-S transition

Question 151

What occurs during the S phase? DNA replication

Question 152

What are the products of DNA replication called? Sister chromatids

Question 153

When do sister chromatids segregate into daughter cells? During mitosis

Question 154

What occurs during the G2 phase? The cell makes preparations for mitosis

Question 155

What happens to cells that do not divide? They usually arrest during G1 and enter G0

Question 156

What is the inactive resting phase of the cell cycle called that some cells enter from G1? G0

Question 157

Can cells in G0 re-enter the cell cycle? If so

Answer 157

under what conditions? Yes

Question 158

Give an example of human cells that typically stay in G0. Cells of the heart (cardiac muscle) and brain (neurons)

Question 159

What did cell fusion experiments reveal about the cell cycle? The existence of internal signals that control the transitions between stages

Question 160

What did the fusion of HeLa cells in S phase with cells in G1 phase show? That a cell in S phase produces a substance that activates DNA replication

Question 161

What phase are the nuclei of cells in that do not undergo DNA replication? G1

Question 162

What phase are the nuclei of cells in that do undergo DNA replication? S phase

Question 163

What hypothesis did Rao and Johnson test in their cell fusion experiments? Answer: That a cell in S phase contains an activator of DNA replication

Question 164

What virus was used in the laboratory to fuse cells experimentally? Answer: Sendai virus

Question 165

What type of cells did Rao and Johnson use in their experiment? HeLa cells

Question 166

What was used to label the DNA of S phase cells before fusion? A radioactively labeled component of DNA (thymidine)

Question 167

What is the role of cyclin-dependent kinases (CDKs) in the cell cycle? They control progress through the cell cycle

Question 168

What type of enzyme is a protein kinase? An enzyme that catalyzes the transfer of a phosphate group from ATP to a target protein

Question 169

What is the transfer of a phosphate group from ATP to a target protein called?Phosphorylation

Question 170

Which transition in the cell cycle is controlled by a particular CDK? The G1-to-S transition

Question 171

What is the control point in the cell cycle called the G1-to-S transition? The restriction point (R)

Question 172

Are CDKs always enzymatically active? No

Answer 172

not unless they are bound to cyclins

Question 173

What are the activator proteins that bind to CDKs called? Cyclins

Question 174

How does cyclin binding activate a CDK? By altering its shape and exposing its active site to substrates (allosteric regulation)

Question 175

Are there different cyclin–CDK complexes in the eukaryotic cell cycle? Yes

Answer 175

that act at different stages

Question 176

Question: What does the G1/S cyclin–CDK catalyze the phosphorylation of?

Question 177

Answer: A protein called retinoblastoma protein (RB)

Question 178

What is the role of the RB protein in many cells at the restriction point (R)?Answer: It acts as an inhibitor of the cell cycle

Question 179

What happens to the RB protein when it is phosphorylated by the G1/S cyclin–CDK Answer: It becomes inactivated

Question 180

Question: What does the inactivation of RB protein allow to happen? Answer: The cell cycle can proceed through the restriction point

Question 181

Question: How is the activity of CDKs primarily regulated? By regulating the presence or absence of cyclins

Question 182

Question: When are cyclins typically present in the cell cycle? Cyclically: they are made only at certain times What are cell cycle checkpoints?

Question 183

Signaling pathways that regulate the cell cycle’s progress

Question 184

Question: How many checkpoints are there during interphase? Three

Question 185

How many checkpoints are there during mitosis? One

Question 186

Give an example of what might cause the cell cycle to pause at a checkpoint. If a cell’s DNA is substantially damaged or a chromosome is unattached to the spindle

Question 187

Question: What happens if DNA is damaged by radiation during G1 at the G1-to-S checkpoint

Question 188

Answer: A signaling pathway results in the production of a protein called p21

Question 189

Question: What does the p21 protein do? It binds to the G1/S CDK

Answer 189

preventing cyclin binding and keeping the CDK inactive

Question 190

What happens when the DNA damage is repaired? p21 breaks down

Answer 190

allowing cyclin–CDKs to function

Question 191

What happens if DNA damage is severe and cannot be repaired? The cell will undergo programmed cell death (apoptosis)

Question 192

What can stimulate cells to divide? Growth factors

Question 193

Are all cells in an organism constantly going through the cell cycle? No. Some enter G0 or divide infrequently

Question 194

What are growth factors? External chemical signals that can stimulate cells to divide

Question 195

Give an example of a situation where growth factors are involved in cell division.Platelets at a wound releasing platelet-derived growth factor to stimulate skin cells to divide and heal or interleukins and erythropoietin stimulating blood cell precursor division

Question 196

How do growth factors exert their effect on the cell cycle? They bind to specific receptors and activate signal transduction pathways that end with cyclin synthesis

Answer 196

thereby activating CDKs and the cell cycle

Question 197

What are CDKs controlled by in the eukaryotic cell cycle? The binding of cyclins

Question 198

Besides internal signals

Answer 198

what else controls the eukaryotic cell cycle? External signals such as growth factors

Question 199

What happens to the G1/S cyclin concentration during the cell cycle? Synthesis begins during G1

Answer 199

it binds to CDK making it active

Question 200

Question: What is a checkpoint trigger in the G1 phase? DNA damage

Question 201

Question: What is a checkpoint trigger in the S phase? Incomplete replication or DNA damage

Question 202

Question: What is a checkpoint trigger in the G2 phase? DNA damage

Question 203

What is a checkpoint trigger in the M phase? Chromosome unattached to spindle